Move player finders to a proper place & optimize them

[noaccessl]

I thought it would be better to move these functions to a specialized place.
There was even a comment about it there.

-- These are totally in the wrong place.

Also, optimized them by using bidirectional mapping between IDs and players for easier fetching and cleanup.

[bloodycop7]

Are you sure this cannot have a client side side effect just like ents.Iterator, invalid entities that even IsValid check doesn't fix

[noaccessl]

Are you sure this cannot have a client side side effect just like ents.Iterator, invalid entities that even IsValid check doesn't fix

Most likely it should never happen as this just clears the certain player from stored data. ents.Iterator invalidates cache entirely, setting recaching up for the next call.

As far as I know, these two hooks shouldn't provide invalid players and only called once (regarding players).